/* * RTP parser for VP9 payload format (draft version 02) - experimental * Copyright (c) 2015 Thomas Volkert * * This file is part of Libav. * * Libav is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * Libav is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with Libav; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #include "libavutil/intreadwrite.h" #include "avio_internal.h" #include "rtpdec_formats.h" #define RTP_VP9_DESC_REQUIRED_SIZE 1 struct PayloadContext { AVIOContext *buf; uint32_t timestamp; }; static av_cold int vp9_init(AVFormatContext *ctx, int st_index, PayloadContext *data) { av_log(ctx, AV_LOG_WARNING, "RTP/VP9 support is still experimental\n"); return 0; } static int vp9_handle_packet(AVFormatContext *ctx, PayloadContext *rtp_vp9_ctx, AVStream *st, AVPacket *pkt, uint32_t *timestamp, const uint8_t *buf, int len, uint16_t seq, int flags) { int has_pic_id, has_layer_idc, has_ref_idc, has_ss_data; av_unused int pic_id = 0, non_key_frame = 0, inter_picture_layer_frame; av_unused int layer_temporal = -1, layer_spatial = -1, layer_quality = -1; int ref_fields = 0, has_ref_field_ext_pic_id = 0; int first_fragment, last_fragment; int rtp_m; int res = 0; /* drop data of previous packets in case of non-continuous (lossy) packet stream */ if (rtp_vp9_ctx->buf && rtp_vp9_ctx->timestamp != *timestamp) ffio_free_dyn_buf(&rtp_vp9_ctx->buf); /* sanity check for size of input packet: 1 byte payload at least */ if (len < RTP_VP9_DESC_REQUIRED_SIZE + 1) { av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet, got %d bytes\n", len); return AVERROR_INVALIDDATA; } /* * decode the required VP9 payload descriptor according to section 4.2 of the spec.: * * 0 1 2 3 4 5 6 7 * +-+-+-+-+-+-+-+-+ * |I|P|L|F|B|E|V|-| (REQUIRED) * +-+-+-+-+-+-+-+-+ * * I: PictureID present * P: Inter-picture predicted layer frame * L: Layer indices present * F: Flexible mode * B: Start of VP9 frame * E: End of picture * V: Scalability Structure (SS) present */ has_pic_id = !!(buf[0] & 0x80); inter_picture_layer_frame = !!(buf[0] & 0x40); has_layer_idc = !!(buf[0] & 0x20); has_ref_idc = !!(buf[0] & 0x10); first_fragment = !!(buf[0] & 0x08); last_fragment = !!(buf[0] & 0x04); has_ss_data = !!(buf[0] & 0x02); rtp_m = !!(flags & RTP_FLAG_MARKER); /* sanity check for markers: B should always be equal to the RTP M marker */ if (last_fragment != rtp_m) { av_log(ctx, AV_LOG_ERROR, "Invalid combination of B and M marker (%d != %d)\n", last_fragment, rtp_m); return AVERROR_INVALIDDATA; } /* pass the extensions field */ buf += RTP_VP9_DESC_REQUIRED_SIZE; len -= RTP_VP9_DESC_REQUIRED_SIZE; /* * decode the 1-byte/2-byte picture ID: * * 0 1 2 3 4 5 6 7 * +-+-+-+-+-+-+-+-+ * I: |M|PICTURE ID | (RECOMMENDED) * +-+-+-+-+-+-+-+-+ * M: | EXTENDED PID | (RECOMMENDED) * +-+-+-+-+-+-+-+-+ * * M: The most significant bit of the first octet is an extension flag. * PictureID: 8 or 16 bits including the M bit. */ if (has_pic_id) { /* check for 1-byte or 2-byte picture index */ if (buf[0] & 0x80) { if (len < 2) { av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n"); return AVERROR_INVALIDDATA; } pic_id = AV_RB16(buf) & 0x7fff; buf += 2; len -= 2; } else { pic_id = buf[0] & 0x7f; buf++; len--; } } /* * decode layer indices * * 0 1 2 3 4 5 6 7 * +-+-+-+-+-+-+-+-+ * L: | T | S | Q | R | (CONDITIONALLY RECOMMENDED) * +-+-+-+-+-+-+-+-+ * * T, S and Q are 2-bit indices for temporal, spatial, and quality layers. * If "F" is set in the initial octet, R is 2 bits representing the number * of reference fields this frame refers to. */ if (has_layer_idc) { if (len < 1) { av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n"); return AVERROR_INVALIDDATA; } layer_temporal = buf[0] & 0xC0; layer_spatial = buf[0] & 0x30; layer_quality = buf[0] & 0x0C; if (has_ref_idc) { ref_fields = buf[0] & 0x03; if (ref_fields) non_key_frame = 1; } buf++; len--; } /* * decode the reference fields * * 0 1 2 3 4 5 6 7 * +-+-+-+-+-+-+-+-+ -\ * F: | PID |X| RS| RQ| (OPTIONAL) . * +-+-+-+-+-+-+-+-+ . - R times * X: | EXTENDED PID | (OPTIONAL) . * +-+-+-+-+-+-+-+-+ -/ * * PID: The relative Picture ID referred to by this frame. * RS and RQ: The spatial and quality layer IDs. * X: 1 if this layer index has an extended relative Picture ID. */ if (has_ref_idc) { while (ref_fields) { if (len < 1) { av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n"); return AVERROR_INVALIDDATA; } has_ref_field_ext_pic_id = buf[0] & 0x10; /* pass ref. field */ if (has_ref_field_ext_pic_id) { if (len < 2) { av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n"); return AVERROR_INVALIDDATA; } /* ignore ref. data */ buf += 2; len -= 2; } else { /* ignore ref. data */ buf++; len--; } ref_fields--; } } /* * decode the scalability structure (SS) * * 0 1 2 3 4 5 6 7 * +-+-+-+-+-+-+-+-+ * V: | PATTERN LENGTH| * +-+-+-+-+-+-+-+-+ -\ * | T | S | Q | R | (OPTIONAL) . * +-+-+-+-+-+-+-+-+ -\ . * | PID |X| RS| RQ| (OPTIONAL) . . - PAT. LEN. times * +-+-+-+-+-+-+-+-+ . - R times . * X: | EXTENDED PID | (OPTIONAL) . . * +-+-+-+-+-+-+-+-+ -/ -/ * * PID: The relative Picture ID referred to by this frame. * RS and RQ: The spatial and quality layer IDs. * X: 1 if this layer index has an extended relative Picture ID. */ if (has_ss_data) { int n_s, y, g, i; if (len < 1) { av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n"); return AVERROR_INVALIDDATA; } n_s = buf[0] >> 5; y = !!(buf[0] & 0x10); g = !!(buf[0] & 0x08); buf++; len--; if (n_s > 0) { avpriv_report_missing_feature(ctx, "VP9 scalability structure with multiple layers"); return AVERROR_PATCHWELCOME; } if (y) { if (len < 4 * (n_s + 1)) { av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n"); return AVERROR_INVALIDDATA; } for (i = 0; i < n_s + 1; i++) { av_unused int w, h; w = AV_RB16(buf); h = AV_RB16(buf + 2); buf += 4; len -= 4; } } if (g) { int n_g; if (len < 1) { av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n"); return AVERROR_INVALIDDATA; } n_g = buf[0]; buf++; len--; for (i = 0; i < n_g; i++) { av_unused int t, u, r, j; if (len < 1) { av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n"); return AVERROR_INVALIDDATA; } t = buf[0] >> 5; u = !!(buf[0] & 0x10); r = (buf[0] >> 2) & 0x03; buf++; len--; if (len < r) { av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n"); return AVERROR_INVALIDDATA; } for (j = 0; j < r; j++) { av_unused int p_diff = buf[0]; buf++; len--; } } } } /* * decode the VP9 payload header * * spec. is tbd */ //XXX: implement when specified /* sanity check: 1 byte payload as minimum */ if (len < 1) { av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n"); return AVERROR_INVALIDDATA; } /* start frame buffering with new dynamic buffer */ if (!rtp_vp9_ctx->buf) { /* sanity check: a new frame should have started */ if (first_fragment) { res = avio_open_dyn_buf(&rtp_vp9_ctx->buf); if (res < 0) return res; /* update the timestamp in the frame packet with the one from the RTP packet */ rtp_vp9_ctx->timestamp = *timestamp; } else { /* frame not started yet, need more packets */ return AVERROR(EAGAIN); } } /* write the fragment to the dyn. buffer */ avio_write(rtp_vp9_ctx->buf, buf, len); /* do we need more fragments? */ if (!last_fragment) return AVERROR(EAGAIN); /* close frame buffering and create resulting A/V packet */ res = ff_rtp_finalize_packet(pkt, &rtp_vp9_ctx->buf, st->index); if (res < 0) return res; return 0; } static void vp9_close_context(PayloadContext *vp9) { ffio_free_dyn_buf(&vp9->buf); } RTPDynamicProtocolHandler ff_vp9_dynamic_handler = { .enc_name = "VP9", .codec_type = AVMEDIA_TYPE_VIDEO, .codec_id = AV_CODEC_ID_VP9, .priv_data_size = sizeof(PayloadContext), .init = vp9_init, .close = vp9_close_context, .parse_packet = vp9_handle_packet };